Die and method of drawing shapes



Nov. 27, 1928.

J. T. MOLTRUP DIE AND METHOD OF DRAWING SHAPES Fi1 ed Sept. 1, 1927 2 Sheets-Sheet 1 \jINVEN Nov. 27, 1928. r 1,692,902 7 J. T. MOLTRUP DIE AND METHOD OF DRAWING SHAPES Filed- Sept. 1, 1927 2 Sheets-Sheet. 2

INVENTOR Patented Nov. 27, 1928.

JAMES T. MOLTRUP OF BEAVER FALLS, TENNSYLVANIA.

,,1 )IE AND METHOD OF DRAWING SHAPES.

Application filed September 1, 1927. Serial No. 216,820.

' The present invention relates broadly'to the art of metal working and more particularly to the art of drawing metal rods, bars and other shapes. It not infrequently happens that a shape which has been subjected to a drawing operation through a die assumes an objectionable curvature longitudinally thereof as soon as the drawing pressure is released. This is objectionable in many cases,

' and particularly where the shape is to be used for pins, shafts and the like, where accuracy is essential. In order to compensate for such curvature, it has heretofore been necessary to subject the shapes to a separate straightening operation.

Attempts .have been made to construct drawing dies mounted to permit universal movement whereby acondition is insured at all times such that the longitudinal axis of the opening through the die coincides with the longitudinal axis of the material being drawn and such that the two axes are parallel to each other and to the line of pull. It has heretofore been thought that when such a condition obtained, the resultant product would approximate the desired condition.

Bya series of experiments, I have found that in many cases, at least, such a condition does not afford any remedy and may actually increase the curvature.- In order to offset the tendency for the bar or other shape to curve longitudinally in one direction, it is necessary to effect a change in the angular relationship between the axis of the drawing die and'the axis of the article and the line of pull. The present invention provides a constructionin which any desired angular change within predetermined limits may be obtained.

In the accompanying drawings, there are shown two preferred embodiments of the present invention, by means of which longitudinal curvature has been successfully eliminated.

In the drawings:

Figure 1 is a front elevation of one form of my invention;

Figure 2 is atran'sverse sectional view on the line II-II of Figure 1;

Figure 3 is a plan view of a die ring;

Figure 4 is a sectional view through the die ring on the line IV-IV of Figure 3;

Figure 5 is a plan View of the die;

Fi ure 6 is a sectional view on the line VI I of Figure 5;

Figure 7 is a view similar to Figure 1, showing a modified embodiment of the invention;'

Figure 8 is a transverse sectional view on the line VTII-VIII of Figure 7 and Figures 9 and 10 are diagrammatic views iillustrating the operation of the improved In accordance with the present invention, there may be provided a. die holder 2 of any desired construction depending upon the construction of the apparatus with which it is to be used. This holder preferably has a tapered outer surface 3, adapted to cooperate with the apparatus as well understood in the art. It is also preferably provided with a taperedopening 4, for the reception of a die ring 5 having an exterior 6 tapered to substantially conform to the taper of the opening 4. The holder 2 is conveniently provided with arbitrary indicia 7 adapted to be read against similar indicia 8 on the die ring, whereby the relative relationship of the parts may be determined.

The tapered walls of the opening 4 in the die holder are concentric with respect to the longitudinal axis 9 thereof.

The die ring 5 is provided with a tapered opening 10, the walls 11 of which are eccen trio with respect to a center line 12 about which the outside surface 6 is described. The wall 11, however, is concentric with respect to the center line 13 of the opening 10 itself.

The die ring 6 is preferably formed with a corrugated portion 6 permitting the die ring when loosened to be turned relatively to the holder 2 any desired amount. Assuming ,marks shows that with a material of given cross sec-- angular relation of the two eccentric lines and the lengths thereof. By means of this construction, it is possible to produce a divergence of a predeterminedmaximum amount in any direction in a circle drawn about the center line 12.

Mounted within the opening 10 is a die 14, having a tapered outer surface 15, conforming to the taper of the wall 11. This taper 1 uniform with respee to a center line 16. The die is formed with a drawing opening 17 which is symmetrical with respect to the center line 18 of such opening, but which is eccentric with respect to the center line 16. Preferably, the eccentricity of these parts is such that the angular relationship between the center lines 16 and 18 is the same as the angular relationship between the center lines- 12 and 13; this being one and one-half de grees in the example given. 1 By reason of this construction, it will be apparent that by rotating the die 14 within the die ring 6, the line of draw may be moved radially in any desired direction with respect to the circle C. If, under a given condition of operation, it is necessary to have the center line 18 conform exactly to the line of draw, this could be obtained by rotating the zero gradation 19 180 with respect to the zero gradation of the die ring. In this manner, theangular offset between the center lines 12 and 13 would be exactly counteracted by the angular ofi'set between the center lines 16 and 18. By rotating the die 14 a lesser amount any intermediate point along a radius of the circle C may be obtained, such for example, as the point P. If this point is half way between the center line 12 and the circle C, it will represent a condition in which the die has been rotated substantially 90 within the die ring 5 from the position shown in Figure 2. This will represent an angular divergence between the line of draw and the center line 18 of approximately threefourths degree. If it is desired to maintain this angular relationship, but to have the point P offset vertically with respect to the line of draw instead of horizontally, the die ring 5 may be rotated within the die holder in one direction or the other, as desired, to bring the point P to the position 72 or p, as will be understood. Any desired intermediate condition may be obtained.

In actual use of the invention. it has been found that the parts may be arbitrarily set and a bar drawn. The bar is preferably marked on one side during the drawing operation and after completion of the drawing operation, the curvature with respect to said is observed. Experience further tion and given composition, a certain adj ustment in one direction or the other will eliminate any curvature. Having drawn one shape and determined the curvature, the deeeaeoa sired adjustment will be made. If the adj ustment is insufficient or is too much, correction may be made accordingly. Since, however, the amount of correction and the direction depends upon the material and upon the characteristics of the machine, it is impossible to give any general rule for all cases. The device, 'however, possesses the ability when properly adjusted to eliminate curvature and produce a straight or substantially straight finished article.

It will be understood that the drawings are illustrative only of the preferred embodiment of the invention and that changes in the construction disclosed therein may be made without departing from the spirit of the invention.

In Figures 7 and 8, one such modification is illustrated. This modification comprises a holder 2 having a plurality of openings f1 therein. The number of openings 1s dependent upon the number of shapes which it is -desired to draw at a single operation, the res ent invention making it possible to raw closely adjacent shapes by reason of the comparatively small amount of room required for mounting the dies and adjusting thesame.

I claim:

1. In a drawing die, a die holder, a die ring adjustably mounted therein and having a bore eccentric to its periphery, and a die in said die ring having a bore eccentric to its periphery.

2. In a die, interfitting die parts each hav ing an opening therethrough eccentric to the center line of the outside of such part, said parts being relatively adjustable to provide a drawing opening having its axis at the desired angle.

3. In a die, tapered interfitting die parts, each having a bore therethrough, the boreof each part being eccentric to the center line of its exterior.

4. In a die, tapered interfitting die parts, each having a bore therethrough, the bore of each part being eccentric to the center line of its exterior, the eccentricity of the respective parts being substantially the same.

5. A die comprising a die ring having a bore eccentrically formed therein, and a die adjustably mounted in said bore.

6. In a die, a die ring having a bore therein, a die adjustably mounted in said bore and provided with a drawing opening eccentric to its periphery.

7. In a die, a die holder having a tapered opening, a die ring in said holder havin a tapered opening, and a die in said die ring having a tapered opening, said two last mentioned openings being eccentric to the center line of said first mentioned opening.

8. In the method of drawing substantially straight shapes, the step comprising chang ing the angular relationship between the center line of the drawing die and the longitudinal axis of the shape to counteract the tendency of the shape to curve.

9. In the method of drawing substantially 5 straight shapes, the steps comprising determining the required angular relationship between the center line of the drawing die and the longitudinal axis of the shape to counteract the tendency of the shape to curve, setting the drawing die to provide such angular relationship, and then drawing the article therethrough.

In testimony whereof I have hereunto set my hand.

JAMES T. MOLTRUP. 

